Insights Blog
-- Browse All Articles --
Physics Articles
Physics Tutorials
Physics Guides
Physics FAQ
Math Articles
Math Tutorials
Math Guides
Math FAQ
Education Articles
Education Guides
Bio/Chem Articles
Technology Guides
Computer Science Tutorials
Forums
Chemistry
Biology and Medical
Earth Sciences
Computer Science
Computing and Technology
DIY Projects
Trending
Featured Threads
Log in
Register
What's new
Search
Search
Search titles only
By:
Chemistry
Biology and Medical
Earth Sciences
Computer Science
Computing and Technology
DIY Projects
Menu
Log in
Register
Navigation
More options
Contact us
Close Menu
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Forums
Other Sciences
Chemistry
Vapor pressure -- How does water still boil at 100°C in an open pot?
Reply to thread
Message
[QUOTE="jbriggs444, post: 6827969, member: 422467"] Saturated vapor pressure is a function of temperature. It is a number that can be computed and measured for ideal circumstances. i.e. closed pot. Water boils when the temperature within the bulk of the water reaches the temperature at which this saturated vapor pressure would be equal to atmospheric pressure. Technically, the relationship is between temperature at a point and the pressure within the fluid at the same point where temperature is measured. If the two are equal then the fluid at that point is "at the boiling point". As has been explained, when the fluid is above the boiling point, small bubbles can expand. [Too small and surface tension can make tinier bubbles deflate despite local saturated vapor pressure exceeding local pressure. Hence the notion of "nucleation points", "superheated water" and water in a clean glass sometimes spontaneously boiling when removed from the microwave] It does not matter whether the kettle is sealed or open at the top. It does not matter whether the surface of the fluid is exposed to dry air or to one atmosphere of saturated steam. It is the temperature and pressure within the bulk of the fluid that matters. With dry air, one has evaporation on the surface. So one does not have equilibrium. One needs a heat source. Like a stove. Or a microwave. Or a Bunsen burner. Water heated on a stove will normally have a temperature gradient. Hotter near the bottom, cooler near the top. Boiling tends to initiate at the hotter, deeper portions of the pot where the temperature first exceeds the boiling point at that depth. [/QUOTE]
Insert quotes…
Post reply
Forums
Other Sciences
Chemistry
Vapor pressure -- How does water still boil at 100°C in an open pot?
Back
Top